Materials Data on Sc2Nb3Si4 by Materials Project

Abstract

Sc2Nb3Si4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sc2+ is bonded to seven Si4- atoms to form distorted ScSi7 pentagonal bipyramids that share corners with four equivalent NbSi6 octahedra, corners with six equivalent ScSi7 pentagonal bipyramids, corners with five equivalent NbSi6 pentagonal pyramids, edges with two equivalent ScSi7 pentagonal bipyramids, edges with three equivalent NbSi6 pentagonal pyramids, faces with two equivalent NbSi6 octahedra, faces with three equivalent ScSi7 pentagonal bipyramids, and faces with three equivalent NbSi6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 46–52°. There are a spread of Sc–Si bond distances ranging from 2.75–2.99 Å. There are two inequivalent Nb4+ sites. In the first Nb4+ site, Nb4+ is bonded to six Si4- atoms to form distorted NbSi6 pentagonal pyramids that share corners with three equivalent NbSi6 octahedra, corners with five equivalent ScSi7 pentagonal bipyramids, corners with four equivalent NbSi6 pentagonal pyramids, edges with three equivalent ScSi7 pentagonal bipyramids, edges with three equivalent NbSi6 pentagonal pyramids, faces with two equivalent NbSi6 octahedra, faces with three equivalent ScSi7 pentagonal bipyramids, and a faceface with one NbSi6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of Nb–Si bond distances ranging from 2.58–2.73 Å. In the second Nb4+ site, Nb4+ is bonded to six Si4- atoms to form NbSi6 octahedra that share corners with four equivalent NbSi6 octahedra, corners with eight equivalent ScSi7 pentagonal bipyramids, corners with six equivalent NbSi6 pentagonal pyramids, faces with four equivalent ScSi7 pentagonal bipyramids, and faces with four equivalent NbSi6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Nb–Si bond distances ranging from 2.65–2.79 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Sc2+, four Nb4+, and one Si4- atom. The Si–Si bond length is 2.44 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Sc2+, four Nb4+, and one Si4- atom. The Si–Si bond length is 2.55 Å. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to two equivalent Sc2+, six Nb4+, and one Si4- atom.